code: def data_nominal_with_quotes(self):
      data, rel_name, expected = self.data_nominal()
      data["attr_nominal_spaces"] = [
          "'red wine'",
          "'hard liquor'",
          None,
          "mate",
          "'hard liquor'",
          "mate",
      ]
      return data, rel_name, expected
  
file_path: scikit-survival/tests/test_io.py
imports: from collections import OrderedDict
  from io import StringIO
  import numpy
  import pandas
  import pandas.testing
  import pytest
  from sksurv.io import loadarff, writearff
  from sksurv.testing import FixtureParameterFactory
label_desc: Use image node_id 2 for calling the DataFrameCases obj's underlying member method code with example usage: obj.data_nominal_with_quotes() and returns: data,  rel_name,  expected